"We believe that the data is saying that crash risk has increased in these states and those crash risks are associated with the legalization of marijuana," Matt Moore, senior vice president with the Highway Loss Data Institute, said.

According to the Chicago Tribune, the institute looked at insurance claims from car collisions between January 2012 and October 2016, and found that, in the years following legalization, claims increased 2.7% in Colorado, Oregon and Washington as compared to states still practicing cannabis prohibition.

But while the numbers appear to show a correlation between legal weed and collision claims, there hasn’t been nearly enough data for researchers, officials or experts to confidently claim total causation.

"It would appear, probably not to anyone's surprise, that the use of marijuana contributes to crashes," Kenton Brine, president of the industry group Northwest Insurance Council that represents insurance providers in Washington, Oregon and Idaho. "It would be difficult to say that marijuana is a definitive factor, lacking a citation, in a significant number of crashes to say that what we're seeing here is a trend."

In addition to a lack of hard data about cannabis use and driving, cannabis advocate Mason Tvert, communications director at the Marijuana Policy Project, says that the researchers also failed to consider the rural-urban divide that may have lead to increased collision claims in places like Washington, Colorado and Oregon, home to densely populated cities, when compared to largely rural states like Idaho, Montana and Wyoming.

"The study raises more questions than it provides answers, and it's an area that would surely receive more study, and deservedly so," Tvert said.

Despite the uncertainties behind the study, Moore is still hoping that state officials and lawmakers will consider the Highway Loss Data Institute research when considering the future of legal weed, but until a proper cannabis breathalyzer or standard for cannabis intoxication is established, the data will continue to be circumstantial.